干湿交替条件下铁氧化对水稻土CO_2排放的影响

Effects of Iron Oxidation on CO_2 Emission in Paddy Soils under Dry-wet Alternation Conditions

以湖北省2种典型水稻土[咸宁市的中稻-冬闲水稻土(第四世纪红壤,XR)和潜江市的中稻-冬闲水稻土(钙质潮土,QR)]为材料,研究土壤干湿交替条件下[土壤落干(孔隙含水率55%)到完全淹水(土水比1∶1)]添加Fe2+对土壤Fe3+、可溶性有机碳(DOC)含量及CO2排放的影响,拟揭示水分转变过程中土壤活性铁氧化对土壤有机碳固持的影响。结果表明,整个培养期间,与CK(不添加Fe2+)相比,添加Fe2+促进了XR和QR土壤中活性铁的氧化,XR和QR土壤中Fe3+平均含量分别较CK提高了133.87%和95.66%。落干期间,与CK相比,添加Fe2+促进了CO2的排放,XR和QR土壤CO2累积排放量分别增加了59.77%和124.48%;促进了土壤DOC的积累,XR和QR土壤DOC平均含量分别提高了42.57%和23.71%。淹水期间,与CK相比,添加Fe2+抑制了CO2的排放,XR和QR土壤CO2累积排放量分别降低了54.03%和35.27%;培养前期促进了土壤DOC的积累,培养后期抑制了土壤DOC含量的积累,总体上XR土壤DOC平均含量降低了35.29%,QR土壤DOC含量提高了16.59%。整个培养期间,添加Fe2+后,XR和QR土壤CO2累积排放量分别降低了43.87%和22.14%。综上,我国南方富含铁氧化物的红壤具有更高的固碳减排潜力。

The effects of Fe2＋ addition in soil on Fe3＋ ,dissolved organic carbon （ DOC ） contents and CO2 emission were studied with Xianning rice field （ XR, red soil） and Qianjiang rice field （ QR, calcareous fluvo-aquic soil） as materials under dry-wet alternation （55% water filled pore space and flooding） conditions, so as to reveal the effect of iron oxidation on organic carbon sequestration during water transformation. The results showed that the addition of Fe2＋ promoted the oxidation of active iron in XR and QR soils, compared with CK （ without Fe2 ＋ ） , the average contents of Fe3 ＋ in XR and QR soils increased by 133. 87% and 95. 66% , respectively. Under drought condition, compared with CK, the addition of Fe2＋ promoted the C02 emission and accumulation of DOC ,the cumulative C02 fluxes from XR and QR soils increased by 59. 77% and 124. 48% , and the average contents of DOC increased by 42. 57% and 2 3 .7 1% Respectively. Under the flooding condition, compared with CK,the addition of Fe2 ＋ inhibited the C02 emission,the cumulative C0 2 fluxes from XR and QR soils decreased by 5 4 .0 3% and 35. 27% , respectively; the addition of Fe2＋ promoted the accumulation of DOC at earlier stage, and inhibited the accumulation of DOC at later stage, the average content of DOC decreased by 35. 29% in XR soil but increased by 1 6 .5 9% in QR soil. During the whole period, compared with CK,the addition of Fe2＋ significantly decreased cumulative C0 2 fluxes in XR and QR soils by 43. 87% and 22. 14% , respectively. The results suggested that red soils with rich iron oxide in southern of China had high potential in organic carbon sequestration.